If I were an anti-gun NY politician, that 2nd letter would probably serve only to alert me to the fact that high capacity magazines were actually still available, and would likely cause me to propose legislation to ban ALL over 10rd magazines to eliminate this legal quandary you've presented.
The last thing you want to do is let those anti-gun legislators know about the various loopholes that they didn't intend to create when they passed the rather ineffective NY AWB (the existence of nearly identical post ban rifles, the fact that the ban on specific military styled models is eluded by the existence of "clone" rifles, redesigned silver soldered muzzle brakes to skirt the flashhider/threading rules, legal pre-ban magazines, etc).